Molecular Interactions between Agaricus bisporus Lectin and Phenolic Acids: The Example of 4-Hydroxybenzoic Acid and p-Coumaric Acid

Abstract The interactions between Agaricus bisporus lectin (ABL) and phenolic acids, 4-hydroxybenzoic acid (4HBA) and p-coumaric acid (p-CA), were found to be non-covalent in nature at neutral pH and ambient temperature according to UV-vis analysis. Secondary structure analysis of the ABL on complexation with 4HBA or p-CA showed a reduction in α-helix content of around 3 and 4%, respectively. Intrinsic fluorescence quenching indicates that the association constant between ABL and 4HBA is stronger (1.27 × 105 M− 1) than ABL and p-CA (1.88 × 104 M− 1), with molecular docking analysis also showing a stronger binding energy (ΔG) for ABL-4HBA (-20.1 kJ/mol) than ABL-p-CA (-16.3 kJ/mol). Docking also suggests that phenolic acid interactions occur in the glucose binding region of ABL, stabilized mainly by multiple hydrogen bonds, notably including Arg103, which is also suspected to be a significant residue in glucose binding. These findings provide valuable insights into the binding behaviour of ABL with naturally occurring phenolic compounds, contributing to a better understanding of its potential bioactive properties in functional foods or as a nutraceutical.